The present invention generally relates to a radius forming system for forming flatwork concrete and cement structures, such as sidewalks, roads, and similar constructions.
Concrete forming systems have been in use for a long time, and include various types of structures, including those made of wood and those made of metal. While wood and metal forms are generally used for forming straight sections, oftentimes it is necessary to form curved sections, with various sized radii. Metal forms are available for forming some curved sections, such as disclosed in U.S. Pat. Nos. 965,979, 2,846,748, and 5,154,837 as are wooden forms, however, generally only very large radii can be formed with such forms.
In order to form curves having a smaller radius, special forms must be constructed, usually of materials that can be used only a single time, such as Masonite®, plywood and “bender board” and often require significant labor to be employed in constructing the form, putting it in place and subsequently removing it.
Plastic forms have been provided for concrete forming systems, to take the place of metal or wood forms. Such forms have various structural features to enhance the rigidity of the forms, to compensate for their reduced rigidity, as compared to metal or wood forms, yet allow the reduced weight and reusability for the forms. Various plastic or flexible forms are disclosed in U.S. Pat. Nos. 4,579,312, 4,712,764, 4,750,703, 4,776,555, 6,021,994, 6,629,681 and 6,866,239.
Plastic forms are well suited for forming curves, however, because of the structural features incorporated into the plastic forms to enhance their rigidity, such forms are useful for forming curves generally where the radius is no less than about 3 feet. Difficulty still arises in trying to construct concrete shapes with radii of less than about 3 feet.